1. Field of the Invention
The invention relates to a method and apparatus for selectively generating bleach for use with a surface cleaning device.
2. Description of Related Art
Oxidizing agents, such as chlorine bleach, for example, are well known for their uses in cleaning and disinfecting materials and surfaces. However, this property also makes the handling, storage and transportation of these chemicals hazardous, especially in a consumer setting such as a residential household. Therefore, it is advantageous to have a system that is able to generate small amounts of an oxidizing agent, such as bleach, at the point of use or on demand, from chemicals that pose no health or safety concerns.
Bleach, whose active ingredient is sodium hypochlorite, can be generated in an electrolytic cell from water and sodium chloride, non-hazardous chemicals. An example of an electrolytic cell for generating sodium hypochlorite is disclosed in U.S. Pat. No. 2,707,790 to Goument. In an electrolytic cell, an external power source is required to initiate the oxidation and reduction reactions that take place at the electrodes. In an electrolytic cell for generating sodium hypochlorite, an electrical potential is applied across the electrodes. An oxidation reaction takes place at the anode, producing chlorine gas and a reduction reaction takes place at the cathode, producing sodium hydroxide. The chlorine gas and sodium hydroxide react to produce sodium hypochlorite. Electrolytic cells of this nature can be made in a variety of sizes from those suitable for use in an industrial scale to a size suitable for use in a residential setting.
Several systems have been disclosed for generating an oxidizing agent at the point of use in an electrolytic cell and spraying the generated agent onto a surface to be cleaned and disinfected. For example, U.S. Pat. No. 3,819,329 to Kaestner et al. discloses a spray sanitizing system that includes an electrolytic cell for instantaneously generating a bactericidal solution wherein the chlorine is substantially in the form of hypochlorous acid rather than hypochlorite by maintaining a low pH. This solution can then be sprayed onto a surface to be cleaned with a hand operable wand. U.S. Pat. No. 6,638,364 to Harkins et al. discloses a vacuum cleaning system for generating electrolyzed alkaline water from an electrolytic cell comprising sodium chloride and water. The electrolyzed alkaline water is sprayed onto a surface to be cleaned and then removed from the surface by suction means. These systems are fairly large and require a wheeled platform or vehicle for transporting the system to different areas to be cleaned.
U.S. Pat. No. 7,008,523 to Herrington and U.S. Pat. No. 7,156,962 Koizumi et al. to disclose an electrolytic system for generating an oxidizing agent at the point of use in a dispenser such as a spray bottle. The Herrington '523 patent discloses an electrolytic cell comprising water and sodium chloride for generating bleach. The bleach can be generated in a separate reservoir and delivered to the dispenser or the bleach can be generated directly in the dispenser. The Koizumi et al. '962 patent discloses an electrolytic cell for generating ozone or active oxygen at the point of use for disinfecting surfaces. The electrolytic cell can be placed in a dispenser such as a spray bottle for generating the ozone or active oxygen directly in the dispenser.
The prior systems discussed above deliver the oxidizing agent generated in the electrolytic cell to a surface to be cleaned by spraying the solution onto the surface. One common form of cleaning in a residential household uses a cleaning pad, such as is used for cleaning bare floors or for scrubbing hard surfaces such as a bathtub or sink. Thus, cleaning pads can be used with these prior systems. However, spraying bleach onto a surface may be hazardous if not carefully applied.